- Reaction score
- 6
Hi there, long time lurker, first time poster here.
Straight down to it.. A friend asked me to add some sockets and additional lights to a small outside office they have tacked onto the side of their attached garage, no problem I thought, apparently the garage already has a DB in it with radial power, and lighting and 2 spare ways.
Alas, not quite as simple as it would seem. Nothing crazy but I am just after some opinions on my two current trains of thought. (I was once an apprentice, have 18th, 2330, AM2, 2391, but I have only recently started doing domestic works again after about 10 years working mostly under 60204 in robotics as an engineer... Somehow this seems harder to bottom out!)
Key info is:
The supply to the house is TT.
The house wasn't always attached to the garage, the existing supply is under the floor of this extension and run from the DB, in a 2.5mm SWA.
Access to the existing board is tricky, the floor above is tiled and the board is directly above a door, in the kitchen.
My first thought was to simply run some 16mm T&E from the existing DB on a 64A MCB, adding a 3rd RCD to the board, this one being a 100mA and just for the garage circuit, then out through some slightly enlarged replacement mini trunking that the entire house to garage extension ground floor has been wired in, to a new DB in the garage. In the garage having a 30mA RCD board with a ring, lighting and a circuit for a panel heater in the office. (Why such a big supply you say? They are muttering/knowing them I prompted them to mutter about wanting an EV charger in the future, from this supply).
I dislike the 6mm earth in this scenario, I believe it is compliant as there is no bonding in the garage to be done and the main bonding is clearly taken care of already at the main DB, but it just doesn't really sit right with me. This is definitely the easiest option.
My second thought was to supply a second DB by the meter. The meter used to be external, now it is internal, but still in it's existing external box with a badly cut hole in the plasterboard of the extension giving access... There isn't a particularly nice way of getting tails from here to a new local DB but I could probably get a hole out of the meter box, stick a henley block inside and run new to a DB just above, out of this in relevant T&E circuits into some boxing up, fished through the bridging extension ceiling and then into the garage/office.. This seems slight more "proper", I'm not sure I like the questionable routing of the meter tails in this scenario. I would probably put them on a 100mA RCD inside the meter box, for belt and braces.
Apologies for the no doubt incoherent ranting, once I get going I tend to brain dump. Also apologies if this seems trivial, I just want to do this in the "most correct" manner, I am toying with moving back towards this kind of work in the future as the dramas and red tape in the industry I'm in now is wearing decidedly thin. Not to mention having been desk based for 2 years now, I am thoroughly sick of it! I am treating these jobs as perfect ways to refresh and enhance my knowledge before venturing outside of the confines of family and friends.
Many thanks,
Tom
Straight down to it.. A friend asked me to add some sockets and additional lights to a small outside office they have tacked onto the side of their attached garage, no problem I thought, apparently the garage already has a DB in it with radial power, and lighting and 2 spare ways.
Alas, not quite as simple as it would seem. Nothing crazy but I am just after some opinions on my two current trains of thought. (I was once an apprentice, have 18th, 2330, AM2, 2391, but I have only recently started doing domestic works again after about 10 years working mostly under 60204 in robotics as an engineer... Somehow this seems harder to bottom out!)
Key info is:
The supply to the house is TT.
The house wasn't always attached to the garage, the existing supply is under the floor of this extension and run from the DB, in a 2.5mm SWA.
Access to the existing board is tricky, the floor above is tiled and the board is directly above a door, in the kitchen.
My first thought was to simply run some 16mm T&E from the existing DB on a 64A MCB, adding a 3rd RCD to the board, this one being a 100mA and just for the garage circuit, then out through some slightly enlarged replacement mini trunking that the entire house to garage extension ground floor has been wired in, to a new DB in the garage. In the garage having a 30mA RCD board with a ring, lighting and a circuit for a panel heater in the office. (Why such a big supply you say? They are muttering/knowing them I prompted them to mutter about wanting an EV charger in the future, from this supply).
I dislike the 6mm earth in this scenario, I believe it is compliant as there is no bonding in the garage to be done and the main bonding is clearly taken care of already at the main DB, but it just doesn't really sit right with me. This is definitely the easiest option.
My second thought was to supply a second DB by the meter. The meter used to be external, now it is internal, but still in it's existing external box with a badly cut hole in the plasterboard of the extension giving access... There isn't a particularly nice way of getting tails from here to a new local DB but I could probably get a hole out of the meter box, stick a henley block inside and run new to a DB just above, out of this in relevant T&E circuits into some boxing up, fished through the bridging extension ceiling and then into the garage/office.. This seems slight more "proper", I'm not sure I like the questionable routing of the meter tails in this scenario. I would probably put them on a 100mA RCD inside the meter box, for belt and braces.
Apologies for the no doubt incoherent ranting, once I get going I tend to brain dump. Also apologies if this seems trivial, I just want to do this in the "most correct" manner, I am toying with moving back towards this kind of work in the future as the dramas and red tape in the industry I'm in now is wearing decidedly thin. Not to mention having been desk based for 2 years now, I am thoroughly sick of it! I am treating these jobs as perfect ways to refresh and enhance my knowledge before venturing outside of the confines of family and friends.
Many thanks,
Tom
Last edited:
